Arsenic is a chemical element with the symbol As, atomic number 33 and relative atomic mass 74.92. Arsenic occurs in many minerals, usually in conjunction with sulfur and metals, and also as a pure elemental crystal. It was first documented by Albertus Magnus in 1250.Arsenic is a metalloid. It can exist in various allotropes, although only the grey form has important use in industry. The main use of metallic arsenic is for strengthening alloys of copper and especially lead. Arsenic is a common n-type dopant in semiconductor electronic devices, and the optoelectronic compound gallium arsenide is the most common semiconductor in use after doped silicon.
The toxicity of arsenic to insects
- Use as a wood preservative
- Used in various agricultural insecticides, termination and poisons
Arsenic and many of its compounds are especially potent poisons. Arsenic disrupts ATP production through several mechanisms. At the level of the citric acid cycle, arsenic inhibits pyruvate dehydrogenase and by competing with phosphate it uncouples oxidative phosphorylation, thus inhibiting energy-linked reduction of NAD+, mitochondrial respiration, and ATP synthesis. Hydrogen peroxide production is also increased, which might form reactive oxygen species and oxidative stress. These metabolic interferences lead to death from multi-system organ failure probably from necrotic cell death, not apoptosis. Long term effect may led to carcinogenic conditions.
An increased appreciation of the toxicity of arsenic resulted in a ban for the use of many products like pesticides.In Sri Lanka As added pesticides are banded.But recently researchers found out that the rice which people consume contain considerable amount of Arsenic due to use of pesticides that contains As.Government authorities says that there is no such a thing & rice is safe to consume.This has created some argument among researchers & government authorities .
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News paper articles
- Arsenic in Sri Lanka Imported Fertilizer
- Sri Lanka: University research finds killer arsenic in imported agrochemicals
- Sri Lanka’s arsenic in rice issue is now in people’s court, expert says